interface.hpp

Go to the documentation of this file.

/*
 * Copyright 2020 Robert Bosch GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
#pragma once
#ifndef FABLE_SCHEMA_INTERFACE_HPP_
#define FABLE_SCHEMA_INTERFACE_HPP_

#include <memory>       // for shared_ptr<>
#include <string>       // for string
#include <type_traits>  // for enable_if_t<>, is_base_of<>
#include <utility>      // for move

#include <fable/conf.hpp>   // for Conf
#include <fable/error.hpp>  // for SchemaError
#include <fable/json.hpp>   // for Json

namespace fable {

// Forward declarations:
class Confable;

namespace schema {

class Interface {
 public:
  Interface() = default;
  virtual ~Interface() = default;

  virtual Interface* clone() const = 0;

  virtual bool is_variant() const { return false; }

  virtual JsonType type() const = 0;

  virtual std::string type_string() const = 0;

  virtual bool is_required() const = 0;

  virtual const std::string& description() const = 0;

  virtual void set_description(const std::string& s) = 0;

  virtual Json usage() const = 0;

  virtual Json json_schema() const = 0;

  virtual void validate(const Conf& c) const = 0;

  virtual bool is_valid(const Conf& c) const {
    try {
      validate(c);
    } catch (...) {
      return false;
    }
    return true;
  }

  virtual Json to_json() const {
    Json j;
    to_json(j);
    return j;
  }

  virtual void to_json(Json&) const = 0;

  virtual void from_conf(const Conf&) = 0;

  virtual void reset_ptr() = 0;
};

template <typename S>
using enable_if_schema_t = std::enable_if_t<std::is_base_of<Interface, S>::value>;

// ------------------------------------------------------------------------- //

class Box : public Interface {
 public:  // Constructors
  Box() = default;
  Box(const Box&) = default;
  Box(Box&&) = default;
  Box& operator=(const Box&) = default;

  Box(Interface* i) : impl_(i) { assert(impl_); }                             // NOLINT
  Box(std::shared_ptr<Interface> i) : impl_(std::move(i)) { assert(impl_); }  // NOLINT

 public:  // Special
  std::shared_ptr<Interface> get() { return impl_; }

  template <typename T>
  std::shared_ptr<T> as() const {
    assert(impl_ != nullptr);
    auto downcast_ptr = std::dynamic_pointer_cast<T>(impl_);
    if (downcast_ptr == nullptr) {
      // If you can't figure out the type of this even from this error, set
      // a breakpoint here in gdb and run:
      //
      //     p dynamic_cast<Interface*>(impl_.get())
      //
      // That will give you something like:
      //
      //     $8 = (fable::schema::Interface *) 0x5555559dfd30 <
      //          vtable for fable::schema::FromConfable<
      //            (anonymous namespace)::NormalDistribution<double>, 0
      //          >
      //          +16>
      //
      // Which is much more specific, since the output of FromConfable and
      // Struct can be equivalent, for example.
      throw SchemaError{Conf{}, this->json_schema(),
                        "cannot dynamic_pointer_cast to type T, got nullptr"};
    }
    return downcast_ptr;
  }

  template <typename T>
  std::shared_ptr<T> as_unsafe() const {
    return std::dynamic_pointer_cast<T>(impl_);
  }

  Box reset_pointer() && {
    reset_ptr();
    return std::move(*this);
  }

 public:  // Overrides
  using Interface::to_json;
  Interface* clone() const override { return impl_->clone(); }
  JsonType type() const override { return impl_->type(); }
  std::string type_string() const override { return impl_->type_string(); }
  bool is_required() const override { return impl_->is_required(); }
  const std::string& description() const override { return impl_->description(); }
  void set_description(const std::string& s) override { return impl_->set_description(s); }
  Json usage() const override { return impl_->usage(); }
  Json json_schema() const override { return impl_->json_schema(); };
  void validate(const Conf& c) const override { impl_->validate(c); }
  void to_json(Json& j) const override { impl_->to_json(j); }
  void from_conf(const Conf& c) override { impl_->from_conf(c); }
  void reset_ptr() override { impl_->reset_ptr(); }

  friend void to_json(Json& j, const Box& b) { b.impl_->to_json(j); }

 private:
  std::shared_ptr<Interface> impl_{nullptr};
};

// ------------------------------------------------------------------------- //

template <typename CRTP>
class Base : public Interface {
 public:
  Base() = default;
  Base(JsonType t, std::string&& desc) : type_(t), desc_(std::move(desc)) {}
  explicit Base(JsonType t) : type_(t) {}
  explicit Base(std::string&& desc) : desc_(std::move(desc)) {}
  virtual ~Base() = default;

  Interface* clone() const override { return new CRTP(static_cast<CRTP const&>(*this)); }
  operator Box() const { return Box{this->clone()}; }

  JsonType type() const override { return type_; }
  std::string type_string() const override { return to_string(type_); }

  Json usage() const override {
    auto required = required_ ? "!" : "";
    if (desc_.empty()) {
      return type_string() + required;
    } else {
      return fmt::format("{}{} :: {}", type_string(), required, desc_);
    }
  }

  bool is_required() const override { return required_; }
  CRTP require() && {
    required_ = true;
    return std::move(*dynamic_cast<CRTP*>(this));
  }
  CRTP required(bool value) && {
    required_ = value;
    return std::move(*dynamic_cast<CRTP*>(this));
  }

  CRTP reset_pointer() && {
    reset_ptr();
    return std::move(*dynamic_cast<CRTP*>(this));
  }

  bool has_description() const { return !desc_.empty(); }
  void set_description(const std::string& s) override { desc_ = s; }
  void set_description(std::string&& s) { desc_ = std::move(s); }
  const std::string& description() const override { return desc_; }
  CRTP description(std::string&& desc) && {
    desc_ = std::move(desc);
    return std::move(*dynamic_cast<CRTP*>(this));
  }

 protected:
  void validate_type(const Conf& c) const {
    if (c->type() != type_) {
      if (c->type() == JsonType::number_unsigned && type_ == JsonType::number_integer) {
        return;
      }

      throw SchemaError{c, this->json_schema(), "require type {}, got {}", type_string(),
                        to_string(c->type())};
    }
  }

  template <typename... Args>
  [[noreturn]] void throw_error(const Conf& c, const char* format, Args... args) const {
    throw SchemaError{c, this->json_schema(), format, args...};
  }

  [[noreturn]] void throw_error(const ConfError& e) const {
    throw SchemaError{e, this->json_schema()};
  }

  [[noreturn]] void throw_wrong_type(const Conf& c) const {
    throw_error(error::WrongType(c, type_));
  }

  void augment_schema(Json& j) const {
    if (!desc_.empty()) {
      j["description"] = desc_;
    }
  }

 protected:
  JsonType type_{JsonType::null};
  bool required_{false};
  std::string desc_{};
};

// ------------------------------------------------------------------------- //

template <typename T>
using enable_if_confable_t = std::enable_if_t<std::is_base_of<Confable, T>::value>;

template <typename T>
using enable_if_not_confable_t = std::enable_if_t<!std::is_base_of<Confable, T>::value>;

template <typename T, std::enable_if_t<std::is_base_of<Confable, T>::value, int> = 0>
auto make_prototype(std::string&& desc = "");

template <typename T, std::enable_if_t<!std::is_base_of<Confable, T>::value, int> = 0>
auto make_prototype(std::string&& desc = "");

}  // namespace schema
}  // namespace fable

#endif  // FABLE_SCHEMA_INTERFACE_HPP_